Ruby would be deeply saddened. She might blame herself for not being able to protect Blake. Weiss would probably be in shock at first, then become more determined to fight against whatever caused Blake's death. Yang would be furious and seek revenge. She has a very close bond with Blake, and her death would likely fuel Yang's anger towards the enemy.
The other characters would have a range of reactions. Pyrrha, if she were still alive in the fanfic's context, would be heartbroken. She would see Blake as a fellow fighter and her death would be a great loss to the cause. Ren and Nora would also be affected. Ren might become more withdrawn, while Nora would be more vocal about their loss and would want to take immediate action. Ozpin would likely view it as a significant setback in the fight against evil and would try to use it as a motivation for the remaining characters to be stronger.
The other members of Team RWBY would be deeply affected. They would start to question their own abilities and the purpose of their fight. Some might withdraw into themselves, like a broken Weiss who shuts out the world for a while. Yang, on the other hand, could become reckless in her pursuit of vengeance, endangering herself and others. Blake would try to hold the team together, but she would also be mourning privately. The other friends and allies in the RWBY universe would also be in mourning. Qrow might blame himself for not being there to protect Ruby, and Ozpin would see it as a great setback in the fight against evil.
Ruby would be devastated. Qrow is her uncle and has been an important figure in her life. She might initially go into denial and then be filled with rage, vowing to avenge his death. She could become more determined than ever to take down Salem, seeing it as the only way to make his sacrifice meaningful.
Nagisa would be completely devastated. She has a very deep connection with Tomoya, and his death would likely cause her to sink into a deep depression. She might even lose the will to live, especially if it happened suddenly. For example, if he died in an accident, she would be left with a sense of emptiness and longing for him.
Uraraka would be heartbroken. She was one of Deku's closest friends. She might lose some of her usual cheerfulness and become more focused on finding out who or what was responsible for his death. She could also struggle with her own self - confidence in using her quirk, as Deku was always an inspiration to her.
The other demigods would be devastated. Percy was like a leader to many of them. Annabeth, his girlfriend, would be heartbroken. She might go on a quest for revenge against whatever or whoever put Percy in the situation where he had to sacrifice himself. The campers at Camp Half - Blood would also be in mourning. They would probably hold a big memorial for Percy. His friends like Grover would be in shock and would feel a great sense of loss.
Hermione would likely be devastated. She might go into a deep state of mourning, but also use her intelligence to try and figure out what led to Harry's death. Ron would be angry and heartbroken at the same time. He'd probably want to seek revenge if there was someone or something responsible.
Edward would be completely shattered. He might lose all sense of purpose and even consider ending his own existence. Jacob would be filled with anger and grief. He might blame Edward and the Cullens for not protecting Bella. Charlie would be heartbroken and would likely be in a state of shock for a long time.
Deku would be devastated. He has always seen Bakugo as both a rival and someone he deeply cares about. His reaction would likely be a mix of extreme grief and guilt. He might feel that he could have done more to protect Bakugo. Kirishima, who is Bakugo's friend, would be heartbroken. He would probably be filled with anger towards whatever caused Bakugo's death and would be determined to make the culprit pay. Ochaco and the other classmates would also be in shock. They would come together to support each other through the difficult time, but they would also feel a great sense of loss as Bakugo was an important part of their class dynamic.
The rest of Team RWBY would definitely be influenced. Naruto's loyalty to his friends, which is a big part of his character, would set an example for the whole team. He could also be a mediator in any conflicts within the team. For example, if Weiss and Blake have an argument, Naruto could use his experience with Sasuke and his other friends to help them resolve their differences. His presence would also attract the attention of other characters in the RWBY world, like the professors at Beacon Academy, who would be curious about his abilities.
The characters would be devastated. Grover, Percy's best friend, would be heartbroken. He might lose his ability to find Pan because of the emotional turmoil. His search for Pan was always connected to his friendship with Percy, and without Percy, he could be lost.